Electrical indicating instrument



May 5, 1936.

l.. H. MIDDLETON 2,040,060

ELECTRICAL INDICATING INSTRUMENT Filed June 22, 1934 lllli l 2161i mum n6 l I tl INVENTOR LESLIE H. MIDDLETON BY HIS ATTORNEYS Patented May 5,1936 ELECTRICAL INDICATING INSTRUMENT Leslie H. Middleton, La Crosse,Wis., assignor, by mesne assignments, to Moto Meter Gauge & EquipmentCorporation, a corporation of Delaware (1935) Application June zz, 1934,serial No. '131,968

12 Claims.

This invention relates to electric gasoline gauge heads comprising apointer type galvanometer responsive to a oat controlled rheostat forindicating liquid level, particularly in gasoline tanks of automotivevehicles, such as shown and described in Cheney Patents No. 1,745,603granted February 4th, 1930, and No. 1,753,402 granted April 8th, 1930,on which the present invention is an improvement.

Objects of this invention are to strengthen the construction of gaugeheads of this character, to increase the torque upon the pointer wherebythe effect of road shocks and vibration thereon is decreased; to improvethe magnetic circuit, and to l5 facilitate adjustment and calibration ofthe instrument.

Other objects will become apparent as the following descriptionproceeds, with reference to the accompanying drawing, in which Figure 1is a front elevation of the instrument with the dial removed;

Figure 2 is an inverted plan;

Figure 3 is a rear elevation; and

Figure 4 is an expanded perspective view of 25 the iiux distributingplate.

'I'he frame of the instrument comprises a metal base plate 6 havingupwardly and laterally extending wings I and 8 on which the magnet coils9 and I0 are mounted, and lower arms II and I2 which are bent forwardlyand then upwardly to receive and support the dial I5. Between the armsIl and I 2 a loop I6 is bent forwardly and upwardly to support the frontbearing of the armature shaft.

A strip of fiber insulation I'I is mounted in back of the frame baseplate 6, between lugs I8 bent back therefrom. A metal backing plate I9has lugs 20 bent forwardly around the insulation strip l'I, and haslateral wings 2| and 22 overlying the base plate wings 'I and 8.

The coil 9 is a constant coil having higher resistance and lessmagnetic, strength than the variable coil I0. These coils each have aniron core in the form of a spool, which is mounted on a bracket 23 of abox corner type. The stem 24 of the core spool extends through anopening in the upstanding ange 25 of the bracket, and is upset or peenedto secure a rigid mounting thereon. The inner disk of the spool isslotted and the metal therebetween bent inwardly to form pole tips 26.

The flux distributing plate 21 shown in Figure 4 is mounted on the plate6 with its branches overlying the wings 1 and 8 of the frame base plate.The base 28 of the bracket of the constant coil 9 is placed over theflux distributing plate, and a. screw 29 inserted from the back of theinstrument passes through registering openings in the wing 2|, the wing1, the plate 21 and the bracket base 28, rigidly securing the constantcoil 9 in position with its core aligned with the armature shaft.

The coil I0 however, is intended to be adjusted and for this reason theholes in the wing 22, the wing 8, and the branch 30 of the fluxdistributing plate are elongated to form slots 35, and the screw 32passes through these registering slots into the base 33 of the bracketfor the coil I0.

The flux distributing plate has a movable eX- tension, the base 34 ofwhich overlies the branch 30 and underlies the base 33, and the screw 32passes therethrough also. This extension has an ear 36 caught betweenthe spool of coil I0 and the bracket flange 25, and through which thestem 24 passes, so that the extension 34 is rigid with the base 33.

Another branch of the flux distributing plate has an integral extension3'I which is turned up toward the outer pole of the constant coil 9. Athird branch 38 is turned up at the bottom of 25 the instrument, betweenthe sides of the loop I6, adjacent to the armature.

The armature 40 comprises a double segment of iron rigidly secured to aspindle 4I journaled in a clock bearing carried by a screw 42 whichextends through the plate 6 and the flux distributing plate 21. Thefront end of the armature spindle is journaled in a clock bearing 43fixed in the loop I6. A pointer 44 and a counterweight 45 therefor arealso rigidly secured to the spindle 4 I.

The clock type bearings are long and rugged, and avoid difliculties ofthe old conical pointed pivots. The parts are held in constant andpermanent alignment, irrespective of magnetic and mechanical forcesacting upon the spindle and bearings.

A loose fly-wheel 46 or inertia dampener, is mounted on the spindle 4Ibetween two collars 41 slightly spaced therefrom. The center hole in thefly-Wheel 46 is slightly larger than the spindle, so that frictionalengagement with the shaft and collars is the only connectionto thespindle.

As the pointer must overcome the natural inertia of the fly-wheel, whichopposes any movement thereof, the same is dampened to' avoid vibrationthereof due to road shocks and jarring.

The lower arms II and I2 of the base plate 6, which form posts tosupport the dial plate I5, are entirely separate and distinct from thegauge movement itself, thereby avoiding any possibility 55 'loV of dialmovement being transmitted to the gauge movement, and preventingsticking and binding. An upper contact stud 48 'passes through the topoi' the insulating strip I1, and a lower or central contact stud 49passes through the frame base plate 9 and the strip l1, the head oi thestud being insulated from the plate 6. Contact tabs 56 are mounted underthe heads of each of these studs, and in electrical contact therewith.

The constant coil 9 has an end grounded to the frame, and the other endconnected by one of the tabs 50 to the central contact stud 49. Thevariable coil I6 is connected to the tank fitting rheostat one end ofwhich is grounded.

As the current is gradually increased through the variable coil I6 duetonlling the gas tank and cutting out resistance in the tank rheostat,

the iield strength trom the tips 26 of the variable` coil I9 isincreased, and this tends to move the amature from a position oppositethe constant coil 9 to a position opposite the variable coil I0.

The pole tips 26 are of advantage in that they are in close proximity tothe armature 40, which serves to concentrate the flux from each coil atthese tips 26. When the tank fitting oat rheostat is in the "emptyposition, there is no current ilowing through the variable coil I0 andthe current owing through the constant coil 9 generates a ideldconcentrated at the tips 26, tending to hold the armature in zeroposition.

The variable coil l0 has corresponding pole tips which concentrate theiield thereof in the same manner. The strength of the eld generated bythis variable coil I0 is dependent upon the current therethrough,in'turn dependent upon the rheostat as controlled by the float in thetank.

These pole tips 26 therefore, serve to concentrate these various fieldforces in the path of the armature. Without these tips 26, the poleswould have to be very close to the armature, to concentrate the flux forthe torque necessary to stabilize the pointer under road shocks andvibrations.

The ilux distributing plate forms a complete iron circuit for themagnetic ilux, and incloses both of the coils and the armature. 'I'hebranch terminating in the bendable tip or integral extension 91, isassociated with the outer pole of the constant coil 9.

'I'he movable extension 96 which is riveted on to the outer pole of thevariable coil l0, having its base 94 movable with respect to the slot 99in the iiux plate proper, results in a sliding connection between theiron core of the variable coil I0, and the flux distributing plate, buta considerable leakage passes between the core of the constant coil 9and this plate, at the bendable tip 91.

'I'he central arcuate branch 98 is associated with the amature 46, andhas its tip curved to approximate the path ot this armature, so thatthere is no change in the air gap between the armature and this uxplate, and no change in the neld strength,.at any point in the armaturepath.

In assembling the instrument, the constant coil 9 is fixed solid in apredetermined definite po- -sition `on the base plate 6, as by means ota jig.

The variablecoil Iissetinanarbitrary position during assembly.

The gauge is calibrated on zero by bending the tip 91 oi' the uxdistributing plate upwards or sideways through a range oi' about onesixteenth of aninchwithrespecttotheouterendotthe iron core spool of theconstant coil 9. Thus4 the zero calibration is eected by bending backand forth the iron circuit connecting it to the main flux circuit.

'I'he screw holding the variable coil in position passes through a slotin the base plate and iiux distributing plate, so that this coil isadjustable for rotation about this screw and also inwardly andoutwardly, so as to obtain the desired overall range on the instrumentin connectionwith the adjustment oi' the constant coil above referredto. 'I'he pointer position when all resistance is cut out from the tankrheostat is adjusted particularly by the position of the variable coil.

The scale range adjustment is made by loosening the screw 92 and movingit along the slots 35, thus moving the var-lame cou lo back and forthfrom the armature to vary the strength of the iiux; and also byswiveling about the s crew 92 as a pivot, to vary the direction of theux, after the lateral adjustment has been obtained.

The full position oi! the pointer and the scale characteristics areadjusted by bending the center branch 99 of the iiux distributing platetoward or away from the amature, to strengthen or weaken the `iiux. Atthe same time, bending the corners oi' this branch 98 in or out permitsa slight ilux directional calibration means for correcting scale errors.

The constant coil 9 may be swung about the ymounting screw 29 as apivot, to adjust the magnetic iield in relation to the ileld of thevariable coil I6, to enable the empty, $41, V2, full positions of thepointer to be calibrated at the desired points on the scale.

While it is essential to move the variable coil I 6 to calibrate thegauge, the vconstant coil need not be moved.

The double pole tips in combination with one swiveling adjustable coiland one coil both swiveling and laterally adjustable enable four poletips to be variable in position with respect to the armature and the twopairs are also variable with respect to each other. Thus these four iluxpaths can be adjusted to give any desired scale calibration.

It should be noted that in addition to the ilux strength adjustment ofthe distance of the coil from the armature, a flux directionaldistribution adjustment is provided, by the pivotal movement of eitherof the coils, and by the corner bending of the flux distributing platetips 91 and 99. 'I'he structure as here described enables themanufacture of a neat, positive, and accurate gas gauge head, whichquickly and positively follows any change in the resistance of the tankiltting rheostat, and by the concentration of ileld strength has amplepower to cause the pointer to take a true reading position without lag,and has suilicient power to overcome pivot friction ordinarily met within a gauge of this type. Accurate readings are thus obtained both withan ascending or descending pointer.

What I claim is: c

1. In an electrical instrument, an amature, a frame, a coil having aconstant ileld excitation and a coil having a variable eld excitation,said coils being located on said frame at an angle to each other, aninflexible mounting for said coil having the constant eld excitation,and adjustable means for moving said coil having the variable ileldexcitation axially toward and away from said armature, and also in aplane perpendicular to the axis of said amature.

2. In an electrical instrument comprising a pointer type galvanometerresponsive to a. iloat controlled rheostat for indicating gasoline tanklevel of automotive vehicles, the combination of a frame, a coil ofconstant excitation and a coil of variable excitation located on saidframe at an angle to each other, means for maintaining said coil ofconstant excitation in xed position on said frame, means for calibratingthe gauge on zero without moving said coil of constant excitation, andadjustable means for moving said coil of variable excitation to altersaid angle and thereby adjust the scale range of said gauge.

3. In an electrical instrument, a frame, a coil adapted to produce aconstant i'leld of force and a coil adapted to produce a variablefieldof force, said coils being located on said frame at an angle toeach other, said coil adapted to produce a variable eld of force havinga slidable pivotal mounting on said frame.

4. In an electrical instrument, a frame, a. coil having means forexciting its winding to produce a constant eld, and a coil having meansfor exciting its winding to produce a variable iield, located on saidframe at an angle to each other, a ux distributing plate having portionsadjacent both of said coils, and means for adjusting the area of saidplate.

5. In an electrical instrument, an armature, a frame, a coil havingmeans for exciting its winding to produce a constant field, and a. coilhaving means for exciting its winding to produce a variable field,located on said frame at an angle to each other, a ilux distributingplate having portions adjacent both of said coils, adjustable means formoving said variable coil with respect to said armature, and means foraltering the relation of the adjacent portion of said flux distributingplate to said constant coil.

6. In an electrical instrument, a frame, an armature, a coil havingmeans for exciting its winding to produce a constant iield, and a coilhaving means for exciting its Winding to produce a variable eld, locatedon said vframe at an angle to each other, a ilux distributing platehaving portions respectively associated with each of said coils and saidarmature, and means for respectively adjusting the relation of saidportions to said constant coil and armature, and

means for adjustably mounting said variable coil on said frame formovement with respect to said amature.

7. In an electrical instrument, an armature, a frame, a coil havingmeans for exciting its Winding to produce a constant field, and a coilhaving means for exciting its Winding to produce a variable field,located on said frame at an angle to each other, a ilux distributingplate associated with said coils and armature, and adjustable meansformoving one of said coils with the associated portion of said platerelative to said armature and to the remainder of said plate.

8. In an electrical instrument, a frame, an armature, a coil of constantexcitation and a coil of variable excitation located on said frame at anangle to each other, one of said coils having a pole tip inclined towardsaid armature in the plane thereof.

9. In an electrical instrument, a frame, an armature, a coil of constantexcitation and a coil of variable excitation located on said frame at anangle to each other, one of said coils having a spool core, portions ofsaid core being bent in- Wardly in the plane of said armature, and meansfor adjusting the position of said coil for altering the flux.

l0. In an electrical instrument, a frame, an armature, a coil ofconstant excitation and a coil of variable excitation located on saidframe at an angle to each other, one of said coils having a spool core,portions of said core being bent inwardly in the plane of said armatureto form pole tips, a iiux distributing plate between said coils andframe, adjustable means for moving said variable coil thereon withrespect to said armature, said flux distributing plate having bendablebranches respectively associated with said constant coil and saidarmature.

1l. In an electrical instrument, a pair of coils mounted at an angle toeachother, one of said coils having a bent pole tip for concentratingthe ilux thereof.

12. In an electrical instrument, an armature and a coil having a spoolcore, a portion of the flange of said spool being bendable in the planeof the armature for altering the ilux.

LESLE H. MIDDLETON.

